Khao Yai National Park is one of the largest in Thailand. It's also a World Heritage Site.
https://en.m.wikipedia.org/wiki/Khao_Yai_National_Park
Driving through this morning, I was hoping to spot some of the wild (and notoriously grumpy, especially with motorbikes!) elephants the park is famous for. No such luck, though... The only ones I found were these rather jolly specimens at the Palad-jang shrine. I did see lots of pig-tailed macaques, and a couple of wild buffaloes, and the road through the rainforest is really beautiful, so well worth the trip here!
